Janosch Ruff

Research Interest

I am interested in theoretical computer science and algorithms. The focus of my research lies on structures that emerge in complex networks, and use these properties to explain why simple algorithms are much more efficient on real-world networks than their worst-case would suggest. To achieve this goal, I work on the beautiful model of Hyperbolic Random Graphs for the average-case analysis of algorithms.

In particular, I enjoy working on randomised algorithms where one observes a threshold behaviour: a change of a parameter on the microscopic level leads to completely different behaviour on the macroscopic scale; a classic example is Percolation Theory.  

I conduct myself under the guideline "Everything should be made as simple as possible, but not simpler".

Publications

[ 2025 ][ 2024 ][ 2023 ]

2026

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  Maus, Yannic; Ruff, Janosch On Distributed Colouring of Hyperbolic Random Graphs Symposium on Discrete Algorithms (SODA) 2026

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2025

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  Berger, Julian; Friedrich, Tobias; Lenzner, Pascal; Paraskevi, Voula; Ruff, Janosch Strategic Network Creation for Enabling Greedy Routing Conference on Artificial Intelligence (AAAI) 2025

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  Baguley, Samuel; Maus, Yannic Maus; Ruff, Janosch; Skretas, George Hyperbolic Random Graphs: Clique Number and Degeneracy with Implications for Colouring International Symposium on Theoretical Aspects of Computer Science (STACS) 2025 

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2024

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  Harder, Jonathan Gadea; Kötzing, Timo; Li, Xiaoyue; Radhakrishnan, Aishwarya; Ruff, Janosch Run Time Bounds for Integer-Valued OneMax Functions Genetic and Evolutionary Computation Conference (GECCO) 2024

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2023

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  Bläsius, Thomas; Friedrich, Tobias; Katzmann, Maximilian; Ruff, Janosch; Zeif, Ziena On the Giant Component of Geometric Inhomogeneous Random Graphs European Symposium on Algorithms (ESA) 2023

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Teaching

As a Lecturer

• Distributed Algorithms, Summer 2023, HPI Potsdam (Lecture: Randomized Coloring)
• Probability and Computing, Summer 2022, HPI Potsdam  (Lectures: Probabilistic Method, Incompressibility Method, Universal Probability)

As a Teaching Assistant

• Probability and Computing, Summer 2022, HPI Potsdam
• Creative Problem Solving, Summer 2022, HPI Potsdam
• Seminar on Theory of Artificial Intelligence, Winter 2021/22, HPI Potsdam

As a Tutor

• Algorithm and Data-Structures, Winter 2018/19, 2019/20, 2020/21, University of Göttingen